[perl #123496] [PATCH] Make "use vstring" for v < 5 or v > 6 an error.

[via RT]

# New Ticket Created by  Konrad Borowski 
# Please include the string:  [perl #123496]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=123496 >


---
 src/Perl6/Grammar.nqp | 32 +++++++++++++++++++++++---------
 src/core/Exception.pm |  7 +++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/src/Perl6/Grammar.nqp b/src/Perl6/Grammar.nqp
index 2000376..69bef42 100644
--- a/src/Perl6/Grammar.nqp
+++ b/src/Perl6/Grammar.nqp
@@ -1576,15 +1576,29 @@ grammar Perl6::Grammar is HLL::Grammar does STD {
         $<doc>=[ 'DOC' \h+ ]**0..1
         <sym> <.ws>
         [
-        | <version> [ <?{ ~$<version><vnum>[0] eq '5' }> {
-                        my $module := $*W.load_module($/, 'Perl5', {}, 
$*GLOBALish);
-                        do_import($/, $module, 'Perl5');
-                        $/.CURSOR.import_EXPORTHOW($/, $module);
-                    } ]?
-                    [ <?{ ~$<version><vnum>[0] eq '6' }> {
-                        $*MAIN   := 'MAIN';
-                        $*STRICT := 1 if $*begin_compunit;
-                    } ]?
+        | <version> [
+                    ||  <?{ $<version><vnum>[0] == 5 }> {
+                            my $module := $*W.load_module($/, 'Perl5', {}, 
$*GLOBALish);
+                            do_import($/, $module, 'Perl5');
+                            $/.CURSOR.import_EXPORTHOW($/, $module);
+                        }
+                    ||  <?{ $<version><vnum>[0] == 6 }> {
+                            my $version_parts := $<version><vnum>;
+                            my $tokens := +$version_parts;
+                            my $position := 1;
+                            while $position < $tokens {
+                                if $version_parts[$position] != 0 {
+                                    $/.CURSOR.typed_panic: 
'X::Language::Unsupported', version => ~$<version>;
+                                }
+                                $position++;
+                            }
+                            $*MAIN   := 'MAIN';
+                            $*STRICT := 1 if $*begin_compunit;
+                        }
+                    ||  {
+                            $/.CURSOR.typed_panic: 'X::Language::Unsupported', 
version => ~$<version>;
+                        }
+                    ]
         | <module_name>
             {
                 $longname := $<module_name><longname>;
diff --git a/src/core/Exception.pm b/src/core/Exception.pm
index 1bc3739..4b26419 100644
--- a/src/core/Exception.pm
+++ b/src/core/Exception.pm
@@ -1614,4 +1614,11 @@ my class X::EXPORTHOW::Conflict does X::Comp {
     }
 }
 
+my class X::Language::Unsupported is Exception {
+    has $.version;
+    method message() {
+        "No compiler available for Perl $.version"
+    }
+}
+
 # vim: ft=perl6 expandtab sw=4
-- 
2.2.1